1. Field of the Disclosure
The disclosure relates to a fireproof glazing unit including at least two transparent substrates spaced from each other, with at least one transparent fireproof layer between the substrates.
2. Related Technology
In order to configure transparent glazing units as fireproof glazing, it is a known to employ laminated glass that has at least one transparent fireproof layer. The effect of such a fireproof layer can be, for instance, that in case of fire, it expands to create a hardening foam that consequently forms a shield against the heat generated by the fire. However, most of the familiar fireproof systems have the drawback that the fireproof layers used are not UV-stable. As a consequence, exposure to sunlight over a prolonged period of time causes the fireproof layer to become cloudy, a phenomenon that greatly impairs the appearance of the glazing. This is particularly disadvantageous when fireproof glazing is used in residential, office or other public areas, where the visual appearance of glass panes is of great importance.
In order to reduce the UV sensitivity of fireproof layers, it is a known procedure to employ various additives in the production of the layers. For instance, DE 44 35 841 proposes the use of potash water glass as an additive for the fireproof layer between two glass panes. Here, the amount of the additive consisting of potash water glass is selected in such a way that, as a function of the prevailing conditions, a detrimental sensitivity to ultraviolet light no longer exists. The main components of the described fireproof layer are soda water glass and water, whereas organic additives in the form of polyvalent alcohols and/or sugars constitute minute residues.
The disadvantage of stabilized protective layers lies in the fact that the production of fireproof layers is always associated with a great deal of effort in view of the process involved. For example, the necessary potassium water glass component has to be precisely determined and adjusted to any changes in the composition of the layer. Moreover, the processes can only be employed for one type of fireproof layer, while other forms require adapted additives or even different solutions.
WO 99/35102 and corresponding JP 111 99 278 disclose a UV-absorbing fireproof glazing in which, in front of a fireproof layer that foams in case of fire, there is a UV-absorbing layer containing the amide compounds of an aminosilane compound that reacts with a UV-absorbing compound. Even though this method is suitable for different fireproof layers, it is very demanding.